The present invention relates generally to a dental hygiene product namely a flexible neck toothbrush. More particularly, the present invention relates to a toothbrush having a handle portion pivotally connected to a neck portion having a dental brush. A leaf spring, interconnected between the handle portion and the neck portion, allows the neck portion to pivot when a threshold pressure is exceeded on the face of the dental brush. The threshold pressure is a pressure upon the dental brush just below that which causes tooth abrasion and gum damage.
Dental disease is one of the most common human medical afflictions. In an attempt to combat dental disease, the brushing of teeth has become a common daily personal hygiene routine. Many people, however, brush their teeth in an improper fashion by applying excessive pressure to the brush which often damages teeth and gums. Excessive brushing force can cause recession and wear of the gums and other soft oral tissues as well as depletion of hard tissues such as tooth enamel, dentin and cementum. Accordingly, it is desirable to brush the teeth with a light pressure and proper bristle orientation to avoid damage to the hard and soft tissues of the mouth.
Improper and overzealous oral hygiene often leads to severe tooth root abrasion and gum recession, resulting in a domino effect of sensitive teeth, avoidance of brushing, root caries, gum problems, pulpal trauma, root canal therapy, weakened teeth, tooth breakage and eventual tooth loss. Even standard home oral hygiene recommendations and equipment can lead and often do contribute to tooth and gum trauma because of a toothbrush user's inability to adapt use of the toothbrush to the arch curvature of the teeth and gums. Most of the focus in the history of tooth brushing has been directed to brush heads, bristles and toothpaste. Recently, the problem with the use of excessive force from the dental brush upon the teeth has been gaining notoriety. While there has been gaining emphasis on improved safety for brushing, prior safety improvements unsatisfactorily added to the cost of the daily dental hygiene, when it is recognized that the average consumer does not typically spend more than a few dollars on a daily use toothbrush. Thus, there is a great need in the art for improved, ergonomic, safer and cost effective brushing devices which allow controlled forces upon the dentition and supporting structures, as well as aiding in the proper orientation of the toothbrush and contacting bristles.
An acceptable range of pressure used during brushing that is not deleterious to the teeth or gums is known. It is difficult, however, without complex pressure sensing equipment to monitor the pressure applied on the brush against the teeth to stay within the acceptable range of pressure. Prior art devices have attempted to address the use of excessive force and pressure at the brush head by providing pressure-sensing devices. In such devices, when a threshold pressure is reached, an electrical signal is produced and an alarm may sound, a light may flash, a vibration may occur, or the toothbrush neck may disengage. Such pressure sensors and biofeedback systems are typically complex and cannot be produced at a price point level that is acceptable to the average consumer. Another force sensing system such as embodied in U.S. Pat. No. 6,327,734 provides a non-electronic means of feedback by providing a snapping sound when excessive force is applied. The feedback simply provides notice that the safe pressure has been exceeded; however, such feedback may be simply ignored by the user.
As is known in the art, other devices have attempted to address reduction of pressure upon the teeth by providing spring-like flexion within the toothbrush neck or base immediately adjacent the dental brush. In the known prior art, these devices typically create increasing torque as the neck, brush and head remain virtually the same distance apart from the handle, and there is only a slight flexion which mitigates the forces, but does not alleviate the problem of over-pressurization because the slight flexion exhibits Hookian spring characteristics. Hookian spring characteristics are defined by Hooke's law of springs which states that the spring force increases in direct proportion to the distance of displacement of the spring.
Current flexible neck toothbrush designs contribute to tooth abrasion and gum recession because brush head pressure increases directly with handle pressure. Electric toothbrushes were designed to remove more plaque with less force than manual brushes; however, many people utilize automatic toothbrushes just as incorrectly as manual brushes by over pressurization which may have a more deleterious effect than a standard toothbrush because of the added motion or vibration of the brush head.
Other prior art devices additionally include elastomer or other rubber like substances sandwiched between links in the brush neck. Many such prior art devices that utilize very soft elastomer aid in reducing brushing trauma but such devices deform too quickly, and take a significant amount of time (minutes to hours) to reset back to normal. Such brushes can be frustrating to the user because during the proper two-minute brushing interval, such brushes can quickly become deformed out of the ideal shape for proper usage. Other types of toothbrush components employing stiffer elastomers result in increasing torque and increasing force consistent with Hookian principles.
Other prior art devices employ biofeedback, which users often ignore, and such devices involve very complicated sliders, pivots and springs to aid in maintaining consistent force. Such devices, however, appear to be valid only over a very small range of motion and further appear to be too complex for simple daily use. Other prior art devices snap out of place at a predetermined threshold force. It appears that such prior art devices might be clumsy and frustrating to use and users may encounter problems if the devices snap back into place.
In each of the prior toothbrushes, the mechanical attempts to mitigate the excessive force of the brush on the teeth fail for the following reasons, among others: 1). The Hookian spring action of “flexible” toothbrush necks causes increasing brush head force with increasing handle force; 2). Inadequate range of motion wherein the neck flexibly occurs over so small a range of motion as to be easily overruled by excessive handle force and improper brushing motions; 3). Excessive flexibility and poor resetting characteristics which allow the brushes to quickly and progressively bend out of shape while taking minutes or hours for resetting; and/or 4). Poor ergonomics which leads to instability, poor gripping, improper brushing, and tissue damage. Thus, there is a great need in the art for a toothbrush which will automatically maintain a physiologically healthy constant brush head force despite widely varying brush handle forces, positions and motions. Further, there is a great need in the art for a toothbrush that can automatically accommodate variations in dental arch structure and curve alignment as well as variations in manual dexterity without the need for complex sensors and biofeedback mechanisms. There is also a great need in the art for a toothbrush which can provide a constant light pressure on the teeth for people with sensitive gums, gum surgery, oral wounds or other oral maladies. There is also a great need in the art for a user-adjustable variable pressure setting that allows one brush to be multifunctional from ultra soft, to soft, to medium, over an infinite range, or with discrete digital increments between to endpoint settings such that one brush can be used for multiple purposes with a single brush accommodating all types of users. Also needed is a brush that is ergonomic and easy to manipulate and orient properly against dental structures. Consumers would thus benefit from the simplicity of a single brush for use over a wide range of pressures to avoid confusion in the shopping experience and to further avoid the clutter and expense of multiple brushes.